Non-invasive pH and temperature mapping is needed for cancer research because these parameters are exploited in tumor diagnosis or therapy. To that goal, smart contrast agents (SCAs) composed of paramagnetic lanthanide ion (Ln3+) with derivatives of 1,4,7,10 tetraazacyclododecane (cyclen) have been developed for MR. We have shown that two commercial Tm3+-based SCAs, TmDOTP5 and TmDOTMA, provide extracellular pH/temperature maps with biosensor imaging of redundant deviation in shifts (BIRDS). These types of SCAs are used as MRS shift agents to separate resonances of endogenous molecules (or ions). However BIRDS maps the 1H signals from non-exchangeable protons (i.e., CHx) of the SCA itself, which is in contrast to the paramagnetic chemical exchange saturation transfer (PARACEST) agent that features exchangeable protons (e.g., OH or NHx). Detection of the non-exchangeable protons by BIRDS provides redundancy to extract temperature/pH, the chemical shift imaging (CSI) data are acquired rapidly for superior signal-to-noise ratio (SNR), and quantification is nearly insensitive to the magnetic field strength (Bo), poor Bo shim conditions, and the SCA's concentration. BIRDS with high speed 2D CSI at 11.7T allows spatial resolution of ~10 <L or better in rat's cerebral cortex with TmDOTP5- (phosphonic acid, high charge) and TmDOTMA- (carboxylic acid, low charge), respectively. Presence of a -CH3 moiety in TmDOTMA- enables about 5W higher SNR. This Yale-Macrocyclics partnership will study four novel Ln3+ cyclen-based complexes. However to map tumors spanning from cortical to subcortical regions in rat brain with ~1 <L spatial resolution - which is within limits of microPET and microSPECT we will first achieve whole brain coverage by combining phased array radio frequency technology with spherically encoded k-space 3D CSI (Aim 1). We will synthesize unique SCAs with improved sensitivity/specificity for pH and/or temperature (Aim 2). These new SCAs (i.e., phosphonate ester and alanine-amide as well as their 19F-labelled analogs) will feature high SNR non-exchangeable protons with two -CH3 moieties, favorable biodistribution by exclusion of phosphonic acids, and improved permeability across the blood-brain barrier (BBB) because of lower SCA charge. Each SCA will then be characterized by MR for its sensitivity to physiological parameter(s), tested for its kinetic inertness, and BBB permeability (Aim 3). Then we will examine their toxicity and biodistribution (Aim 4). Finally we will apply these SCAs to study 9L and CNS-1 tumors in rat brain (Aim 5). The proposed work in rats are the gateway to pre-clinical development and translation to humans is on the horizon because there are clear industrial signs for molecular imaging with BIRDS or PARACEST agents. The final product of the proposed work would help identify the most probable structural features with acceptable toxicology and biodistribution. If this type of pre-clinical development is successful, then it would represent huge paradigms in diagnostic human imaging.